What I'll explain here is how to turn a basic Linux system into a router, and add firewall functionality with iptables (netfilter). It's based on a Debian 3.0 installation, but should apply to other distributions as well. If you get confused about Debian Linux, About Debian has a very good collection of beginner's guides.
When BB-router is used to create home LAN environment, PCs on LAN are connected to the WAN via BB-router with network address translation (NAT). For such case, PC's network interfaces on the LAN are served by static IP or DHCP from the BB-router. BB-router must be configured to connect the WAN following the instruction by your ISP. Modem/3G - Debian Wiki Though this section needs work, it documents how one Debian user connects to the Internet over NTelos' cellular network in the United States using a Franklin CDMA EV-DO U210 USB modem. NTelos uses Sprint's network, and moreover it would appear that Franklin's U210 is the base model of Franklin's U-series (U210, U600, U601, U602, U770, U772), so How to Restart Networking in Debian Linux – Linux Hint On recent Linux distributions such as Debian 9 Stretch, networking can be managed by the Network Manager. It makes configuring a network really easy. Network Manager has command line utilities for network configuration. If you have minimal server version of Debian 9 Stretch installed, you may not have Network Manager installed. Debian As Router | cyberspace
FRR Debian repository
Modem/3G - Debian Wiki Though this section needs work, it documents how one Debian user connects to the Internet over NTelos' cellular network in the United States using a Franklin CDMA EV-DO U210 USB modem. NTelos uses Sprint's network, and moreover it would appear that Franklin's U210 is the base model of Franklin's U-series (U210, U600, U601, U602, U770, U772), so How to Restart Networking in Debian Linux – Linux Hint
Debian -- Details of package upnp-router-control in jessie
How to make Ubuntu/Debian as a router - Blogger In addressing the router enables wireless networking connection, really amazing what Technology has changed these days. I like meeting new things. This is why i have come to this blog, I find it very interesting.This is like How To Configure Linux as a Static Router – devconnected This means that the first host is contacting the router on the 192.168.200.1/24 IP address and that second host is contacting the router on the 192.168.190.1/24 IP address. First of all, you have to identify the network interfaces used for routing Debian -- The Universal Operating System Debian is a free operating system (OS) for your computer. An operating system is the set of basic programs and utilities that make your computer run. Debian provides more than a pure OS: it comes with over 59000 packages, precompiled software bundled up in a nice format for easy installation on your machine. Read more